source: node_modules/prismjs/components/prism-antlr4.js

Prism.languages.antlr4 = {
        'comment': /\/\/.*|\/\*[\s\S]*?(?:\*\/|$)/,
        'string': {
                pattern: /'(?:\\.|[^\\'\r\n])*'/,
                greedy: true
        },
        'character-class': {
                pattern: /\[(?:\\.|[^\\\]\r\n])*\]/,
                greedy: true,
                alias: 'regex',
                inside: {
                        'range': {
                                pattern: /([^[]|(?:^|[^\\])(?:\\\\)*\\\[)-(?!\])/,
                                lookbehind: true,
                                alias: 'punctuation'
                        },
                        'escape': /\\(?:u(?:[a-fA-F\d]{4}|\{[a-fA-F\d]+\})|[pP]\{[=\w-]+\}|[^\r\nupP])/,
                        'punctuation': /[\[\]]/
                }
        },
        'action': {
                pattern: /\{(?:[^{}]|\{(?:[^{}]|\{(?:[^{}]|\{[^{}]*\})*\})*\})*\}/,
                greedy: true,
                inside: {
                        'content': {
                                // this might be C, C++, Python, Java, C#, or any other language ANTLR4 compiles to
                                pattern: /(\{)[\s\S]+(?=\})/,
                                lookbehind: true
                        },
                        'punctuation': /[{}]/
                }
        },
        'command': {
                pattern: /(->\s*(?!\s))(?:\s*(?:,\s*)?\b[a-z]\w*(?:\s*\([^()\r\n]*\))?)+(?=\s*;)/i,
                lookbehind: true,
                inside: {
                        'function': /\b\w+(?=\s*(?:[,(]|$))/,
                        'punctuation': /[,()]/
                }
        },
        'annotation': {
                pattern: /@\w+(?:::\w+)*/,
                alias: 'keyword'
        },
        'label': {
                pattern: /#[ \t]*\w+/,
                alias: 'punctuation'
        },
        'keyword': /\b(?:catch|channels|finally|fragment|grammar|import|lexer|locals|mode|options|parser|returns|throws|tokens)\b/,
        'definition': [
                {
                        pattern: /\b[a-z]\w*(?=\s*:)/,
                        alias: ['rule', 'class-name']
                },
                {
                        pattern: /\b[A-Z]\w*(?=\s*:)/,
                        alias: ['token', 'constant']
                },
        ],
        'constant': /\b[A-Z][A-Z_]*\b/,
        'operator': /\.\.|->|[|~]|[*+?]\??/,
        'punctuation': /[;:()=]/
};

Prism.languages.g4 = Prism.languages.antlr4;